Within the project, 7 different Work Packages (WP) were designed and are being developed:
WP1: The waste streams from the food industry are completely characterized in terms of their physico-chemical properties and microbial load. Moreover, wastes pretreatment and provision processes are developed to produce rich in nutrients substrates, suitable for microbial fermentation and production of PHAs. Among the pretreatment technologies, innovative enzymatic processes for the hydrolysis of the organic load of wastes are also included.
WP2: The recovered substrates are exploited in order to optimize the PHAs production processes, using pure cultivations. Fermentations are performed using wild-type and genetically modified strains, which are further optimized through statistical Design of Experiments (DoE). The production rate is maximised in aerobic bioreactors via the application of semi-continuous feeding policies, while a mathematical simulation model is also developed for the same scope.
WP3: In parallel with the previous WP, the pretreated wastes are used in two-step mixed cultivations, under a continuous operating mode. In the first anaerobic step of the process, the simultaneous acidification of sugars and production of bio-hydrogen are performed. In the second step, the rich in fatty acids effluent of the former step is utilized as the substrate for the optimal production of PHAs.
WP4: Subsequently, the issue of intracellular PHAs recover and characterization is addressed. In particular, different recovery methods, including typical thermo-chemical extraction, sonication and novel enzymatic and microbial processes, are evaluated in terms of their recovery yield and effect on PHAs properties. After their recovery and purification, PHAs are characterized with respect to their composition, structure and molecular, thermal, mechanical, etc., properties, as well as their biodegradability.
WP5: Initially, the size and geometry of the produced packaging products, the appropriate moulding conditions and biopolymer specifications are identified via tests on commercial PHAs. Subsequently, before final formulation, the mechanical properties of PHAs are optimized via their mixing or by using plasticizers. Packaging end-products are evaluated through their application to simulated and real foods.
WP6: The integrated process for the co-production of PHAs and H2 is scaled-up to a new pilot unit (which is equipped with automated monitoring and control systems). This unit is designed, installed and operated continuously in two steps (stages), with an emphasis on the bioconversion of sugars-containing wastes.
WP7: The conceptual design and simulation of bioprocesses leads to the selection of optimal scenarios for the two developed value chains. Moreover, via the use of an appropriate simulation software, the biorefinery's technical and economic viability is assessed, and the life-cycle analysis (LCA) of the end-products and processes is carried out.